Work holder



June 15, 1948.J B. c. LENDO Em. 2,443,582

WORK HOLDER Filed Sept. 11, 1944 Patented June 15, 1948 UNITED STATES PATENT OFFICE WORK HOLDER Application September 11, 1944, Serial No. 553,614

ll Claims. 1

This invention relates to work holders and, more particularly, to Work holders of the kind used for holding component metal parts in place while they are being connected together and is especially useful for holding such parts for welding together by the use of gas flames or metal electrodes.

In the fa-brication of various structures by welding together component parts formed of steel or steel alloy, it is important that the parts be held in their proper relation to each other during the welding cycle or operation. Since such parts are subject to expansion and contraction during the welding it has heretofore been necessary to provide the welding jigs or fixtures being used, With a flexible or yieldable means for holding such component parts in a manner to permit such expansion and contraction. This has involved the use of heavy and expensive apparatus including locating pads or brackets together with mechanical clamps for the work pieces, and spring means located either in the clamps or in the mountings for the pads or brackets so as to provide the necessary flexibility for expansion and contraction. The production of fabricated struc-' tures by the use of this previous apparatus was slow inasmuch as several manual Operations were required and in many instances the pads, clamps or other parts of the apparatus interfered with the accessibility of the portions of the work to be joined or welded.

The present invention eliminates these difiiculties by providing a novel form of work holder in which electromagnets are employed for holding the various work pieces in the desired relation and in a manner to permit expansion and contraction to readily take place, and such that the work portions to be joined or welded will be freely accessible for the Operations to be performed thereon.

Another object of this invention is to provide a novel form of magnetic work holder in which a plurality of electromagnets mounted in an arrangement corresponding generally with the shape of the work structure to be produced, support and hold the component work pieces in position for the welding cycle or operation and yet permit expansion and contraction to take place.

Still another object of this invention is to provide a novel work holder of this Character which is of a simple and economical construction and the use of which reduces the time and labor required in producing various kinds and types of welded assemblies.

Other objects and advantages of the invention tions.

will be apparent from the following description when taken in conjunction with the accompanying drawing in which Fig. 1 is a perspective view showing the novel work holder of the present invention being used in the production of a fabricated work structure;

Fig. 2 is a partial side elevation showing one of the electromagnets of the apparatus;

Fig. 3 is a transverse sectional view taken on line 3-3 of Fig. 2;

Fig. 4 is a side-elevation, with portions bro-ken away, showing a modified form of construction for the electromagnets of the improved work holder; and

Fig. 5 is a plan view of one of the modified electromagnets.

AThe work holder of the present invention can be used in the production of various structures to be fabricate'd from bars, tubes or the like, of steel, steel alloy or other magnetic materials and is especially suitable for rapidly and economically producing welded structures for aircraft such as fuselage frame, landing gears, engine mounts, Wing structures and various other parts or sec- Fig. 1 shows one embodiment of the novel work holder IO being used in the fabrication of a work structure H. The work structure is in the form of a polygonal frame which, in this instance, is in the shape of a triangle and is formed by three tubes or bars, 12, |3 and l4 made of steel, steel alloy or other magnetic material and connected together by welds 15.

As shown in the drawing, the work holder Io comprises a frame or support 6 and a plurality of electromagnets l'l mounted on such frame. The frame IG corresponds generally in shape -or form with the Work structure being produced or fabricated, and since the work structure ll shown in this instance is of triangular shape, the frame or support IB is also of triangular form. The frame 16 can be of any appropriate construction and as here shown may comprise a plurality of structural members or channels IB, l9 and 20 which are welded or otherwise rigidly secured together.

The electromagnets I'l are mounte'd on the frame IB in spaced relation and are so disposed relative to each other that they likewise assume an arrangement corresponding generally in shape with the polygonal shape of the frame Hi and the work structure to be fabricated. In the particular form of Work holder shown in F'ig. 1, one of the electromagnets l'l is mounted on each of the frame members |8, 19 and 2B at or adjacent the mid-point of the side of the polygon formed by such frame mmher, i

f frame i members. receiving'portions which are shaped to correspond Each of the electromagnets I'I comprises a pair of spaced pole members 2|, 22 and an energizing winding or coil 23. The pole pieces 2| and 22 form extensions of a core 24 around which the energizing winding 23 is disposed. The magnets Il may be mounted on the frame IS by providing appropriate brackets 25 on the respective frame members and which are welded or otherwise attached thereto. The magnets are connected'to the brackets 25 by the use of a pair of spaced insulating clips 26 and 21 which are bolted or otherwise attached to the brackets and against which the pole members 2| and 22 are clamped, as 'by extending the threaded ends of the core 213 through such pole members and clips and applying clamping nuts 28 thereto.

As will be seen from the drawing, the electromagnets ll are mounted on the respective frame members l, |9 and 20 so that their pole members 2| and 22 are spaced apart longitudinally of such Thepole members have work with the Work pieces intended to' be held.` In this instance, .the work'piecesi; IS and I fi are cylindrical in shape 'and the pole members 2! .and 22 aretherefore provided with arcuate recesses 29 in whichthe workv pieces are snugly received. These'farcuate recesses provide an increased area, of metal-to-metal contact between the work and the pole memberssoas to render the clamping action of 'the electromagnets more effective.

From the arrangement vas thus ardescribed, it will be seen also that the pole members 2! and v22 of each magnet` are engaged and spanned by an intermediate portion of one of the workpieces while other portions of the workv piece project outwardly or l'ongitudinally in overhanging relation to the lpole members. with suchprojecting portions of one work piece extending substantially into engagement or welding relation with 'the imderstood of course that our invention contemplates that any desired number of electromagnets can be employecl and that the principle of the invention'can be applied to work holders for the fab'rication of work structures of various other polygonal shapes.

A suitable energizing circuit or circuits (not shown) is provided for the electromagnets Ill and it is obvious that these electromagnets can be energized separately-by the use of individual con- 'trol switches or simultaneously by the use of a contro1 switch common to all of the magnets. Leads 3 and 32 are shown in Fig. 2 for -the magnetizing winding 23.

In Figs. 4 and a modified form of electro- 'magnet 35 is shown which can be usedvon the frame I 6 instead of the electromagnets Il of Fig. 1. The modified electromagnet 35 comprises a standard 36 having energizing coils 31. and a work supporting header. lbracket' 38' :thereorL The istandardf: is here'shown as being madezof iron pipe sections 39 and 4B whiclrare-:connected'by a, pipe coupling 4! so as to provide for adjustment of the height at which the head 38 is supported above the frame E5. A locknut 5,2 cooperates with the coupling M for looking the pipe sections at the desired height adjustment. The lower end of the standard 36 can be connected with the frame lt as by means of the pipe flange '33.

The work receiving head 38, which is preferably made of non-magnetic material such as brass, includes a sleeve :portion [54 mounted on the pipe section 39 by means of the clarnping screws and spaced arm portions lit adapted to receive therebetween a magnetizable work piece fal with the latter spanning the upper end of the pipe section 39. The arms 66 can be provided with spring-pressed work gripping elements l8 as shown in the drawings. The magnetizing coils 37 are disposed around the pipe section 39 which forms a pole member and such coils are preferably housed in a shell lit! or the like which is made of non-magnetic material. The modified magnets 35 are mounted on the frame members in spaced pairs so that the pole members of the magnets will be spanned by .the work pieces and when the coils 'l of the magnets 35 are energ'ized the magnetic circuits will include portions of the frame members.

During the useof our improved work holder the work pieces can be quickly and easily assembled in theirproper relative po-sitions by placing the same in the recessed pole members of the respective magnets. These recessed pole members locate vthe work pieces in their proper general positions and serve as guides whichpermit the workvpieces to be easily slid in the directio'n of their longitudinal axes to bring them into their substantially .exact positions With respect to each other for the welding cycle. When the magnets are energized the work pieces will be securely held in their prearranged relation so that the welding cycle can be carried out without likelihood of the work pieces being disturbed during the welding. An important advantage of our work holder is that the holding action produced by the electromagnets permits expansion and contraction of the work pieces during the welding operation and,yupon completion of the welding cycle, the deenergization of the magnets imme- `diately releases the fabricated work structure for quick and easy removal from the work holder.

While we have illustrated and'described our irnpi'oved work holder inmore or less detail, it will be understood, of course, that we do-not wish to be correspondingly 1imited, but regard our invention as including all changes and modifications coming within the spirit of the invention and the scope of the appended elaims.

Having thus described our invention, we claim:

l. A work holder of the characterdescribed -comprising, a frame, a plurality of magnets said intermediate portions being `longitudinally shiftable in said top recesses during expansion and contraction of the work pieces.

2. A work holder of the character described comprising, a polygonal frame correspoding generally in Shape With a polygonal work structure to be produced by welding together work pieces of magnetic material of bar form, electromagnets mounted on said polygonal frame at intermediate points of the sides thereof, sai'd electromagnets having magnetizing windings and pole members, said pole members being spaced apart in the direction of the sides of said polygonal frame and having top recesses therein for receiving and holding said Work pieces with intermediate portions of said work pieces spanning the spaces between the pole members and other portions projecting beyond the pole members and extending into Welding relation to each other, said intermediate portion's 'being longitudinally shiftable in said top recesses during expansion and contraction of the work pieces and alone forming armatures on which the magnetic attraction of the magnets acts for holding the Work pieces in said reoesses.

3. A Work holder of the oharacter described comprising, a polygonal frame of magnetic material corresponding generally in shape with a polygonal work structure to be produced by welding together work pieces of bar form, .pairs of electromagnets mounted on said frame at intermediate points of the sides thereof, said electromagnets comprising standards connected with said frame and provided with pole members at their upper ends and magnetizing coils on said standards, said pole members being spaced apart in the direction of the sides of said polygonal frame and having recessed upper ends for receiving and holding said work pieces with intermediate portions of said work pieces spanning the spaces between the pole members and other portions projecting beyond the pole members and extending into welding relation to each other.

4. A work holder of the Character described comprising, a plura'lity of frame members connected together so .as to form the sides of a frame of polygonal plan shape, a plurality of electromagnets mounted on sai'd frame at substantially the midpoints of the sides thereof, said magnet comprising magnetizing winding means and a pair of pole members spaced apart in the direction of one of the sides of the frame and said pole members having top recesses therein shaped to receive and support a Work ipi'ece of magnetic material of bar form With an intermediate portion of such work piece spanning the pole members and with other portions projecting beyond the pole members and extending into Welding relation to corresponding projecting portions of Worki pieces held by the other magnets, said intermediate portions 'being :longitudinally shiftable in said top recesses during expansion and contraction of the Work pieces and alone forming armatures on which the magnetic lattraction of the magnets acts for holding the work pieces in said recesses.

BENJAMIN C. LENDO. FRANK PIZMOI-IT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 810,319 Blazej Jan. 16, 1906 1,119,4'70 Swantusch Dec. 1, 1914 1,343,346 Buckley June 15, 1920 1,956,840 Walmsley May 1, 1934 2,160,405 Mallalieu May 30, 1939 2,254,314 Reed Sept. 2, 1941 2,383,008 Meister Aug. 21, 1945 OTHER, REFERENCES Weld. Encyclopedia, 11th edition, pub. 1943, Weld. Eng. Pub. Co., Chicago, Ill., p. 319. 

